Transmitters

Before we discuss transmitters it is worth considerng the difference between sensors and transmitters. 

We consider a sensor to be the device that reacts to the change in physical change and converts it into some basic form of electronic change. Transmitters usually contain a sensor and all the relavant electronics to convert the change in sensor signal to a singnal that can be transmitted to the real world. Transmitter refers therefore to any device that outputs a signal that is representative of the measurement. Eg. a device that measures pressure and outputs a signal that is representative of the pressure could be considered to be a pressure tramsmitter.